A Review of the Strain Diversity and Pathogenesis of Chicken Astrovirus

Abstract

Although a relatively recently emerged virus, identified only in 2004 as a separate species of avian astrovirus, chicken astrovirus (CAstV) has been associated with poor growth of broiler flocks, enteritis and diarrhea and is a candidate pathogen in cases of runting stunting syndrome. More recently CAstV has been implicated in cases of two other diseases of broilers as the sole etiological agent, namely severe kidney disease of young broilers with visceral gout and the "White Chicks" hatchery disease. Examination of the strains of CAstV associated with the two latter diseases reveals they are closely related genetically. This review will discuss the pathogenesis of CAstV in relation to strain diversity and the effects of vertical versus horizontal transmission, virus load, co-infections and age of bird at infection, all factors that may impact upon disease severity.

Keywords: chicken astrovirus; pathogenesis; strain diversity.

Figure 1

Chicken astrovirus (CAstV) open reading frame (ORF) 2 amino acid sequence. Phylogenetic tree of CAstVs based on complete ORF 2 (capsid) amino acid sequences. The tree was constructed using Geneious v6.1.8 (Biomatters, Auckland, New Zealand) using the neighbor-joining method and 1000 bootstrap replicates (bootstrap values are shown on the tree). Avian nephritis virus serotype 1 (ANV-1) was used to root the tree. * Denotes the Polish CAstV strain associated with White Chicks.